50 years ago today, the Atlas rocket boosters that John Glenn, inside his Friendship 7 capsule, was strapped to the top of ignited. Millions of Americans watched as the resulting 350,000 pounds of thrust vibrated the vehicle that was about to take the first American into orbit around the Earth.
CAPCOM (Capsule Communicator): 3… 2… 1… 0.
John Glenn: Roger. The clock is operating. We’re underway.
Minutes later, John Glenn became the fifth human in space and the first American to enter Earth orbit. Previously, Alan Shepard and Gus Grissom became the first and second, respectively, Americans in space; however, John Glenn was the first American to reach the important milestone of completing orbits of the Earth.
For the next 4 hours and 55 minutes, John Glenn completed three orbits of the Earth, reaching speeds greater than 17,000 miles per hour. NASA was still concerned about the effects of spaceflight on humans and this was the longest one an American astronaut had been subjected to yet. John Glenn remarked a number of times during the mission that he felt just fine, and was rather enjoying himself.
Five minutes into the mission:
John Glenn: Oh, that view is tremendous!
John Glenn witnessed three sunsets from space during the flight.
John Glenn: The sky above is absolutely black, completely black. I can see stars though up above.
John Glenn: This is Friendship Seven. At this, MARK, at this present time, I still have some clouds visible below me, the sunset was beautiful. It went down very rapidly. I still have a brilliant blue band clear across the horizon almost covering my whole window. The redness of the sunset I can still see through some of the clouds way over to the left of my course. Over.
From his fantastic vantage point, he observed dust storms and fires in Africa and the lights of Perth, Australia.
And then there was his “fireflies”, which he first noticed at about 1 hour and 15 minutes into the flight:
John Glenn: This is Friendship Seven. I’ll try to describe what I’m in here. I am in a big mass of some very small particles, that are brilliantly lit up like they’re luminescent. I never saw anything like it. They round a little: they’re coming by the capsule, and they look like little stars. A whole shower of them coming by.
They swirl around the capsule and go in front of the window and they’re all brilliantly lighted. They probably average maybe 7 or 8 feet apart., but I can see them all down below me, also.
CAPCOM: Roger, Friendship Seven. Can you hear any impact with the capsule? Over.
John Glenn: Negative, negative. They’re very slow; they’re not going away from me more than maybe 3 or 4 miles per hour. They’re going at the same speed I am approximately. They’re only very slightly under my speed. Over.
They do, they do have a different motion, though, from me because they swirl around the capsule and then depart back the way I am looking.
Are you receiving? Over.
There are literally thousands of them.
These “fireflies”, as Glenn called them after the mission, were later determined to be ice crystals that would accumulate on the craft on the dark side of the Earth and then begin to break off of the capsule when the Sun’s heat returned. 1
Back on the ground, serious considerations were being made. A flight controller received a warning from a sensor on Friendship, indicating a loose heat shield. If the sensor was correct in its reading, the only thing holding the heat shield in place was the straps from the retrorocket package. After debate, a decision was made; Glenn was instructed to refrain from jettisoning the retropack — a normal procedure for re-entry — in hopes that it would hold the heat shield in place during re-entry; the alternative was the craft and Glenn disintegrating in the Earth’s atmosphere. Control offered no explanation for the procedure until after successful re-entry. Glenn suspected a problem with the heat shield, but remained focused on the parts of the craft he could control.
CAPCOM: This is Texas Cap Com, Friendship Seven. We are recommending that you leave the retropackage on through the entire reentry.
John Glenn: This is Friendship Seven. What is the reason for this? Do you have any reason? Over.
CAPCOM: Not at this time; this is the judgment of Cape Flight.
The sensor ultimately proved to be faulty and the heat shield remained securely attached to Friendship. 2
Aside from using more fuel than expected for attitude corrections, a hot spacesuit that had to be regularly adjusted for cooling, and excess cabin humidity, the rest of the flight was essentially flawless.
Glenn fired his retrorockets and descended back to Earth. He splashed down in the Atlantic, 40 miles downrange from the expected landing site. The USS Noa reached Friendship seventeen minutes later and hoisted it onto the ship. Glenn was supposed to exit the capsule from the top hatch, but instead decided to blow the side hatch instead. With a loud bang, the hatch blew open and Glenn emerged and jumped to the deck of the Noa. With a smile, his first words were: “It was hot in there.”
Glenn returned to a hero’s welcome and a ecstatic ticker-tape parade in New York City. Americans were energized with the progress in the race with the Soviets. And with John Glenn’s help, America — and mankind itself — took another step forward into the uncharted heavens above.
*This post was originally published February 20, 2011. Small updates have been made since then.
- In fact, it was solved during the next Mercury mission, Aurora 7, by Scott Carpenter. To test his theory, he banged on the side of the capsule and watched as they broke off of the exterior of the craft! ↩
- And it provided a nice fireworks show for Glenn during re-entry. “My condition is good, but that was a real fireball, boy. I had great chunks of that retropack breaking off all the way through.” ↩